JPH07312880A - Micro actuator, micro pickup, and information storage device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a microactuator that positions the probe of the micro pickup of the information storage device used for high-density recording, the applied voltage can be easily controlled and the time required for positioning is shortened. An object is to provide a microactuator. A polygonal moving plate 2 and a beam 7a which elastically supports the moving plate 2 and which has a fixed end on the substrate inside the moving plate 2.
7c and electrodes 8a to 8 which are arranged in parallel or at an angle to each side of the moving plate 2 and which are attracted by the moving plate 2 by electrostatic force.
g and voltage applying means (not shown) for selectively applying a voltage to the electrodes 8a to 8g. [Effect] A predetermined rotation angle can be obtained at high speed with easy applied voltage control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microactuator manufactured by an IC manufacturing method such as etching or lithography, and a pickup which can be used as a micropositioner in a multiprobe head of a scanning probe microscope or a pickup head of an information storage device. The present invention relates to a device and an information storage device capable of ultra-high density recording using the pickup device.

[0002]

2. Description of the Related Art In recent years, microactuators have been variously studied from the object of interest merely as a research, as a substitute for existing devices and their parts, and for the purpose of positively utilizing the advantage that they can operate at a minute distance in a minute area. Has been researched to be applied to other products. Among them, the application as a pickup when performing ultra-high-density recording with a scanning probe microscope is required much more as the information storage device continues to increase in capacity and the device is required to be downsized. Is coming.

A conventional microactuator will be described below. As a conventional example, Japanese Patent Laid-Open No. 6-38561
The microactuator disclosed in Japanese Patent Application No. 4-183349 is cited. FIG. 6 is a plan view schematically showing this microactuator.

In FIG. 6, 101 is an anchor.
102a to 102c are spiral beams. A moving plate 103 includes a ring portion 107 and an arm portion 110. The moving plates 1 are denoted by 104a to 104i.
The number of the electrodes is circumferentially provided around 03, and wirings are respectively made to these electrodes 104a to 104i by a voltage applying means (not shown). It is possible to arbitrarily select and apply a voltage. You can The moving plate 103 is supported by the anchor 101 provided concentrically with the electrodes 104a to 104i by three beams 102a to 102c of the same shape arranged around the moving plate 103 at intervals of about 120 degrees. These beams 102a to 102c have a spiral shape with a width of about several μm, and are arranged point-symmetrically with respect to the centers of the circumferential electrodes 104a to 104i.

The inner diameter of the electrodes 104a to 104i is the moving plate 1
It is set to be several μm larger than the outer diameter of 03. 1
Reference numeral 05 is a substrate. The moving plate 103 includes beams 102a-
A circular shield layer (not shown) provided on the surface of the substrate 105 between the ring portion 107 and the substrate 105 via 102c and the anchor 101 is configured to always obtain electrical conduction. Further, the shield layer is shown. Not grounded by wiring. Further, an insulating film 106 is provided on the inner circumference of the electrodes 104a to 104i so as not to make direct electrical contact with the moving plate 103. A probe 111 forms a recording pit on a recording medium (not shown) and reads it.

The operation of the microactuator constructed as above will be described below. FIG. 7 is a diagram for explaining the operation of the conventional microactuator. In FIG. 7, first, the electrodes 104a and 104
When the same voltage is applied to b and excited, the ring portion 107 of the moving plate 103 is electrostatically attracted to these electrodes and moves in the OA direction until it contacts the insulating film 106, as shown in FIG. At this time, the position regulating portion 108 of the moving plate 103 causes the electrode 1
By contacting with the guide portion 109 of No. 06 and the outer periphery of the ring portion 107 being in close contact with the electrodes 104a and 104b,
The moving plate 103 is guided to a predetermined position and is surely initialized. At the same time, the probe 111 provided at the tip of the arm 110
Is guided to the position 112a shown in the figure.

Next, when the set of electrodes to be excited is shifted by one electrode, the ring portion 107 revolves in the direction of the arrow X while being attracted by the two excited electrodes. At this time, the ring part 1
07 moves while rolling contact with the electrodes 104a to 104i, the outer circumference of the electrode 07a and the electrodes 104a to 104i.
It will rotate by the amount of the difference in length from the inner circumference. Then, the rotation direction becomes the direction of the arrow Y, which is opposite to the revolution direction, and the probe 111 moves to the position 112b.

In the same manner, by sequentially shifting the set of electrodes to be excited by one electrode, the ring portion 107 is rotationally driven stepwise, and the positions of the probes 112a to 11a.
It can be positioned at 2h. Further, in this conventional example, the pitch angles of the electrodes 104a to 104i are set to a predetermined angle so that the probes 111 can be positioned at equal pitches.

[0009]

However, in the above-described conventional structure, since it is necessary to sequentially switch the electrodes to which the voltage is applied in order to rotate the moving plate, the voltage control becomes complicated and the rotation speed is limited by the control speed. It had a problem that it would end up.

An object of the present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide a microactuator, a micropickup, and an information storage device which can be easily controlled and can be positioned at high speed.

[0011]

In order to achieve this object, a microactuator of the first invention comprises a movable plate having a polygonal outer periphery provided on a substrate, and the movable plate within the movable plate. A beam elastically supported inside the circumference and having a fixed end on the substrate inside the inner circumference of the moving plate; an electrode arranged on each side of the moving plate outside the moving plate; And a voltage applying means for selectively applying a voltage.

Further, in the micro pickup of the second invention, a movable plate having a polygonal outer periphery provided on a substrate, an arm integrally provided on at least one side of the movable plate, and the movable unit are provided. A beam that elastically supports the plate inside the inner periphery of the moving plate and that has a fixed end on the substrate inside the inner periphery of the moving plate, and is arranged outside the moving plate for each side of the moving plate. And an electrode, a voltage applying means for selectively applying a voltage to the electrode, and a probe provided at the tip of the arm.

Further, in the information storage device of the third invention, a movable plate having a polygonal outer periphery provided on the substrate, and an arm integrally provided on at least one side of the movable plate, A beam that elastically supports the movable plate inside the inner periphery of the movable plate and has a fixed end on the substrate inside the inner periphery of the movable plate, and on each side of the movable plate outside the movable plate. A micro-pickup characterized by comprising an electrode arranged, a voltage applying means for selectively applying a voltage to the electrode, and a probe arranged at the tip of the arm, and a micro-pickup close to the probe. The disk-shaped rotary recording medium is arranged, and a rotating unit for rotating the disk-shaped rotary recording medium is provided.

[0014]

With this configuration, the microactuator of the first invention can determine the rotation angle of the moving plate by selecting the electrode to which the voltage is applied. In addition, the micro pickup of the second invention can determine the position of the probe at the tip of the arm portion by selecting the electrode to which the voltage is applied.

Further, the information storage device of the third invention records and reproduces information as a circumferential pit row at a position positioned by the micropickup of the second invention on the disk-shaped rotary recording medium. Will be able to.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 are a top view and a cross-sectional view, respectively, of a micro pickup according to an embodiment of the present invention, in which the same parts are designated by the same reference numerals.

In FIGS. 1 and 2, reference numeral 1 denotes a substrate. In this embodiment, a silicon wafer is thermally oxidized by 1 μm and a silicon nitride film is laminated by 1 μm.
The width is 00 μm and the width is 1000 μm. A moving plate 2 is made of polycrystalline silicon having a thickness of 2.5 μm. The moving plate 2 includes a polygonal portion 3 and an arm portion 4. The polygonal portion 3 has a regular octagonal shape in this embodiment, and the distance between opposite sides thereof is 130 μm. Reference numeral 5 is a shield electrode, which is grounded by a wiring (not shown). An anchor 6 is formed on the lower shield electrode 5 and electrically connected to it.

Reference numerals 7a to 7c are movable plate support beams, which are spiral in this embodiment, and which have the anchor 6 as a fixed end to elastically support the movable plate 2 and also connect the movable plate 2 and the anchor 6 to each other. Also has the function of. Electrodes 8a to 8g are connected to a voltage control circuit (not shown) through wiring (not shown). The shortest distance between the electrodes 8a to 8g and the polygonal portion 3 is 3 μm. Reference numeral 9 is a protrusion provided on each side of the polygonal portion 3, and 10 is a groove corresponding to the protrusion 9. These projections 9 and grooves 10 prevent the displacement of the polygonal portion 3 of the moving plate and the electrodes 8a to 8g when they are attracted by electrostatic force. Reference numeral 11 is a probe for forming and reading recording pits. In this embodiment, the distance between the probe 11 and the center of the anchor 6 is 882 μm.

Reference numeral 12 is a signal electrode, which is used for recording with the probe 11.
Transmits the playback signal. Reference numerals 13a, 13b and 14a denote electrodes, and the electrode 14b is similarly arranged on the side surface of the electrode 14a on the side of the arm 4 substrate 1. Reference numerals 15a and 15b are piezoelectric thin films having a bimorph structure in which the arm portion 4 is sandwiched therebetween. As is well known, since the piezo element has the property of expanding or contracting depending on the direction of the electric field, the arm portion 4 is held in a grounded state and the electrodes 13a, 13b, 1
By appropriately applying positive and negative voltages to 4a and 14b, the electric field applied to the piezoelectric thin films 15a and 15b is controlled to freely expand and contract the bimorph forming portion of the arm portion 4, and the piezoelectric thin film has extremely high resolution. Since it has, the probe 11 at the tip can be precisely driven to scan the sample. Reference numeral 16 is an insulating layer, which is composed of a polycrystalline silicon thermal oxide film and a silicon nitride film in this embodiment, and is electrically conducted when the polygonal portion 3 of the moving plate 2 is attracted to the electrodes 8a to 8g by electrostatic force. I try not to do it. In this embodiment, the insulating layer has a thickness of 0.5.
μm.

The operation of the microactuator constructed as above will be described with reference to FIG. FIG. 3 shows how the micro-pickup operates when a voltage is applied to the electrode 8e. In FIG. 3, the same parts as those in FIGS. . 17a to 17g are probe positions when a voltage is applied to the electrodes 8a to 8g.

When a voltage is applied to the electrode 8e, the polygonal portion 3
Is attracted to the electrode side 8e by an electrostatic force, and is finally adsorbed to the electrode 8e as shown in FIG. The position of the probe 11 at the tip of the arm portion 4 at this time is the position of the side of the polygonal part 3 to be attracted when no voltage is applied (hereinafter referred to as the origin position) and the electrodes 8a to 8g. It is determined by the shortest distance of the position when the electrode 8a to 8g and the angle formed by the sides of the polygonal portion 3 when the polygonal portion 3 is at the origin position.

Therefore, in this embodiment, in order to position the probe 11 every 14.3 .mu.m, the electrodes 8a to 8g have a positive counterclockwise direction with respect to each side of the polygonal portion.
2.1 degrees, -1.4 degrees, -0.7 degrees, 0.0 degrees, 0.9
The angles are 2.6 degrees, 3.1 degrees. After all, when a voltage is applied to the electrodes 8a to 8g, the probe 11 is positioned to the probe positions 17a to 17g at every 14.3 μm. After that, the electrodes 13a, 13b, 1 of the arm portion 4 are
By applying a voltage to 4a and 14b, the probe position is further scanned by a minute distance of ± 7.15 μm from the positioned position. In the present invention, this 14.3 μm width is 190
Recording pit rows are formed at intervals of about 75 nm.

With such a structure, the probe position can be uniquely determined by selecting the electrode to which the voltage is applied, and it is necessary to switch the voltage and rotate the moving plate as in the conventional case. Since it is eliminated, the control becomes extremely easy, and the time required for positioning the probe is shortened.

As described above, according to this embodiment, the anchor, the octagonal moving plate supported by the spiral beam having the fixed end, and the predetermined angle with respect to the seven sides of the moving plate. By providing the electrodes arranged by attaching, the position of the probe at the tip of the arm can be accurately positioned every 14.3 μm by simply selecting the electrode to which the voltage is applied, and the electrodes are sequentially switched. There is no need to do so, the control of voltage application becomes easy, the time required for positioning is shortened, and high-speed positioning is realized.

(Embodiment 2) An information storage device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a perspective view of an information storage device according to an embodiment of the present invention.

In FIG. 4, reference numeral 18 denotes a disk-shaped recording medium, which has a structure in which a thin film of molybdenum disulfide is formed on a conductive support, for example. In this embodiment, single crystal Si is used as the conductive support, and its diameter is about 10 m.
m. Reference numeral 19 denotes a rotating mechanism, and the recording medium 18 is connected to a shaft of a rotating mechanism 19 composed of, for example, a servo motor and is rotated at a predetermined speed.

Reference numeral 20 is a pickup device, and the pickup device 20 is provided between the recording medium 18 and the rotating mechanism 19 at a predetermined distance from the recording surface of the recording medium 18. Reference numeral 21 denotes a housing, and the recording medium 18, the rotating mechanism 19, the pickup device 20, etc. are provided inside the housing 21, and the rotating mechanism 19 is fixed to the bottom surface of the housing 21. Reference numeral 22 denotes a pick-up device supporting portion, which is fixed to the wall surface of the housing 21.

Next, FIG. 5 shows a schematic structure of the pickup device 20. In FIG. 5, reference numeral 23 is the micro pickup described in the first embodiment. As shown in FIG. 5, a plurality of rows of micro pickups 23 are arranged in two rows. In this embodiment, 50 micro pickups are arranged in two rows, but only a part of them is shown in the figure. Since the movable distance of the probe of each micro-pickup 23 is 100 μm and the vertical length of each micro-pickup is 200 μm, it is possible to perform recording on the recording medium 18 without a gap by such an arrangement. A circuit 24 controls the operation of each micro pickup and processes a signal obtained from the micro pickup. Reference numeral 25 denotes a substrate, which is single crystal silicon in this embodiment.

The operation of the information storage device configured as above will be described below. First, the recording medium 18 is rotated by the rotating mechanism 19. Next, when an instruction to read or write information is input through a wiring (not shown) connected to the circuit 24, the circuit 24 drives the micro pickup 23 in accordance with the instruction. First, one of the micro pickups 23 to be operated is selected, and the position of the probe 11 of the selected micro pickup 23 is determined by applying a voltage to any of the electrodes 8a to 8g. In this way, after positioning the probe every 14.3 μm, the circuit 24 is used to position the electrodes 13a, 13b, 14
An appropriate voltage is applied to a and 14b, the arm portion 4 bends toward the recording medium 18, and the probe 11 contacts or approaches the recording medium 18.

In the case of the present embodiment, the probe 11 and the recording medium 18
The distance between the rotating recording medium 18 and the probe 11 is always maintained by detecting the tunnel current flowing between them and controlling the voltage applied to the electrodes 13a, 13b, 14a, 14b appropriately by the circuit 24 so as to keep it constant. Is to be constant. Further, the voltage applied to the electrodes 13a, 13b, 14a, 14b is changed, and the arm 4 is made to scan a minute distance in a direction parallel to the diameter of the recording medium 18 to reach a desired position on the recording medium 18. 11 is moved to read or write information.

In the present embodiment, the reading of information is carried out by detecting the unevenness of the surface, and the read signal is sent back to the circuit 24 through the signal electrode 12 and binarized, and then, from the wiring (not shown). It is output to the outside. Also,
In the present embodiment, the writing of information is performed by applying a voltage to the probe to form minute holes as a circumferential pit row on the recording medium 18.

As described above, a plurality of the micro pickups shown in the first embodiment are arranged in parallel, and a pickup device in which a circuit for drive control and signal processing is formed on the same substrate is brought close to a disc-shaped rotary recording medium. By arranging them side by side, a small-sized and large-capacity storage device can be realized.
In particular, since the positioning of the probe of the micro pickup is simplified, high-speed positioning is possible, and the circuit for controlling the operation of the micro pickup can be simplified.

Although the projection 9 is provided on the polygonal portion 3 and the groove 10 is provided on the electrodes 8a to 8g in the first embodiment, the configuration is reversed to provide a groove on the polygonal portion and a projection on the electrode. May be. Further, although the shapes of the protrusions 9 and the grooves 10 are triangular in this embodiment, they may be, for example, semicircular, semielliptic or rectangular. Further, although the polygonal portion 3 is a regular polygon, the electrodes 8a to 8g may be arranged in a regular polygonal shape, and each side of the polygonal portion 3 may be provided with a necessary inclination.

In the second embodiment, only one micro pickup is operated at the time of recording / reproducing, but a plurality of micro pickups may be operated at the same time. Although a thin film of molybdenum disulfide is used as the recording medium, a thin film of gold, tanbusten diselenide, HOPG (highly oriented graphite), or the like, which is obtained by epitaxially growing the thin film, may be used.

[0036]

As described above, in the microactuator of the first invention, the rotation angle of the moving plate can be accurately determined by selecting the electrode to which the voltage is applied.

Further, in the micro pickup of the second invention, the position of the probe at the tip of the arm can be determined by selecting the electrode to which the voltage is applied, and the voltage application can be controlled easily and at high speed. Positioning is possible.

Further, the information storage device of the third invention records and reproduces information as a circumferential pit row at a position positioned by the micropickup of the second invention on the disk-shaped rotary recording medium. Will be able to
It is easy to control, and a compact and large-capacity storage device can be realized.

[Brief description of drawings]

FIG. 1 is a plan view of a micro pickup according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the same embodiment.

FIG. 3 is a diagram showing an operation of the embodiment.

FIG. 4 is a perspective view of an information storage device according to a second embodiment of the present invention.

FIG. 5 is a plan view of a pickup device according to the same embodiment.

FIG. 6 is a plan view of a conventional microactuator.

FIG. 7 is a diagram showing an operation of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Moving plate 3 Polygonal part 4 Arm part 5 Shield layer 6 Anchor 7a-7c Beam 8a-8g Electrode 9 Protrusion 10 Groove 11 Probe 12 Signal electrode 13a, 13b, 14a, 14b Electrode 15a, 15b Piezoelectric thin film 16 Insulation Layers 17a to 17g Probe position 18 Disc-shaped recording medium 19 Rotation mechanism 20 Pickup device 21 Housing 22 Pickup device support 23 Micro pickup 24 Circuit 25 Substrate

Front page continuation (72) Inventor Shinichi Mizuguchi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A moving plate having a polygonal outer periphery provided on a substrate, elastically supporting the moving plate inside the inner periphery of the moving plate, and on the substrate inside the inner periphery of the moving plate. A micro having a beam having a fixed end, an electrode arranged on each side of the moving plate outside the moving plate, and voltage applying means for selectively applying a voltage to the electrode. Actuator. 2. The microactuator according to claim 1, further comprising a protrusion provided on either one of the sides of the electrode and the polygonal moving plate, and a groove into which the protrusion is fitted, on the other side. 3. The microactuator according to claim 1, wherein an arm is integrally provided on at least one side of a movable plate having a polygonal outer periphery. 4. A movable plate having a polygonal outer periphery provided on a substrate, an arm integrally provided on at least one side of the movable plate, and an inner periphery of the movable plate. A beam elastically supported on the inside of the movable plate and having a fixed end on the substrate inside the inner periphery of the movable plate; an electrode arranged on each side of the movable plate outside the movable plate; A micro pickup comprising: a voltage applying means for selectively applying a voltage; and a probe arranged at the tip of the arm. 5. A movable plate having a polygonal outer periphery provided on a substrate, an arm integrally provided on at least one side of the movable plate, and an inner periphery of the movable plate. A beam elastically supported inside the movable plate and having a fixed end on the substrate inside the inner periphery of the moving plate; an electrode arranged on each side of the moving plate outside the moving plate; For selectively applying a voltage, a micro pickup comprising a probe arranged at the tip of the arm, a disk-shaped rotary recording medium arranged in proximity to the probe, An information storage device, comprising: rotating means for rotating the disk-shaped rotary recording medium.